The heart of the church, where Mass is offered three times a day. The altar was given in 1878 by Lord Bute, who donated the then very large sum of £1000 for the purpose. In 1966 it was moved forward and shortened somewhat, but it remains an impressive block of black veined marble. Behind the altar is the tabernacle, which is also part of the original furnishing of the church and once stood on the High Altar. Around the tabernacle is perhaps the most distinctive feature of the church, the reredos, crowded with statues of saints and angels, and reminding us of the unity of the Church on earth with the Church in heaven. These statues were once coloured, as were the saints in the 'portholes' above, but all were, unfortunately maybe, included in the new all-over grey colour scheme of 1954, and remain that colour today. The fine crucifix and candlesticks date from the early days of the church; the crucifix is now sited in the throne where the monstrance used to be placed for Exposition of the Blessed Sacrament. The marble and alabaster altar rails are another surviving original feature.

Just outside the altar rails is the pulpit.